JP2010115010A - Power supply control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply control unit for suppressing fluctuation in voltage after an engine is started. <P>SOLUTION: The power supply control unit supplies the power accumulated in a battery to a load of a vehicle. The power supply control unit includes a step-up means and a control means. The step-up means boosts the voltage of power supplied from the battery and supplies it to a load. The control means controls a voltage which is boosted by the step-up means. The control means controls the target voltage which the step-up means boosts to a first voltage before the engine of a vehicle is started, and after the engine of the vehicle is started, the target voltage is changed to a second voltage being lower than the first voltage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power supply control device that supplies electric power to an electric load, and more particularly, to a power supply control device that is mounted on an idle stop vehicle that temporarily automatically stops an engine of the vehicle when the vehicle is stopped.

  Conventionally, a starter for starting a vehicle engine is mounted. The starter is supplied with electric power for driving from a battery mounted on the vehicle. In addition to the starter, the vehicle is provided with various electric loads, and the electric load from the battery or the generator is also supplied to the electric load.

  Here, the starter mounted on the vehicle is an electric motor that rotates and starts an engine in a stopped state, and has a large starting current for rotating the engine. Therefore, when the starter is driven, the voltage drop of the battery becomes large, and the voltage of the electric power supplied to other electric loads also decreases. Here, in a vehicle with an idling stop mechanism that automatically stops the engine of the vehicle when the vehicle stops, the number of times that the above-described voltage drop occurs increases because the engine is started a large number of times.

  In order to prevent such a voltage drop of the battery voltage, an idle stop vehicle is disclosed in which a voltage compensation circuit is operated to compensate the battery voltage (see, for example, Patent Document 1). The idle stop vehicle disclosed in Patent Document 1 compensates the battery voltage by operating a voltage compensation circuit (boost circuit) when the battery voltage falls below a predetermined set value.

For example, as shown in FIG. 9, the vehicle is provided with a battery 800 that supplies the stored power to the load 900, and the booster circuit 200 is provided on the power supply line that supplies the power from the battery 800 to the load 900. Is provided. The boosting operation of the booster circuit 200 is controlled by the control unit 100. The control unit 100 controls the start / end of the boosting process based on a boosting signal obtained from another control device (for example, a control device for an idling stop mechanism that controls starting and stopping of the engine). The control unit 100 monitors the output voltage Vo output from the booster circuit 200 during the boosting process, and controls the boosting operation of the booster circuit 200 so that the output voltage Vo becomes equal to or higher than a predetermined target voltage. To do. Specifically, during the boosting process, the control unit 100 causes the booster circuit 200 to start a boosting operation when the output voltage Vo <target voltage, and performs the boosting operation to the booster circuit 200 when the output voltage Vo> target voltage. Stop.
JP 2002-38984 A

  However, the idling stop vehicle disclosed in Patent Document 1 generates voltage fluctuation (ripple) by performing a boosting operation after cranking is completed at the start of the engine. Due to such voltage fluctuations after starting the engine, the light of the vehicle, the lamp provided on the instrument panel, etc. may blink, or noise may occur in the audio equipment of the vehicle.

  For example, as shown in FIG. 10, when the battery voltage Vb drops when the starter is driven, power of the output voltage Vo obtained by boosting the battery voltage Vb to the target voltage by the boosting operation by the booster circuit is output. When the starter driving is finished after the engine is started, the battery voltage Vb rises, and when the output voltage Vo> the target voltage, the boosting operation by the booster circuit is stopped, but the minute change in the output voltage Vo after the engine is started. Therefore, when the output voltage Vo <target voltage, the boosting operation by the boosting circuit is resumed. At this time, the difference between the output voltage Vo and the target voltage may be small, and voltage fluctuation (ripple) occurs due to energy at the time of re-boosting in the booster circuit.

  Therefore, an object of the present invention is to provide a power supply control device that suppresses voltage fluctuations after engine startup.

In order to achieve the above object, the present invention has the following features.
1st invention is a power supply control apparatus which supplies the electric power accumulate | stored in the battery to the load of a vehicle. The power supply control device includes boosting means and control means. The booster boosts the voltage of power supplied from the battery and supplies the boosted voltage to the load. The control means controls the voltage boosted by the boosting means. The control means controls the target voltage boosted by the boosting means before starting the engine of the vehicle to the first voltage, and changes the target voltage to a second voltage lower than the first voltage after starting the engine of the vehicle.

  According to a second invention, in the first invention, the battery voltage monitoring means is further provided. The battery voltage monitoring means monitors the voltage of power supplied from the battery. The control means changes the target voltage from the first voltage to the second voltage when the voltage monitored by the battery voltage monitoring means rises to a threshold value after dropping.

  According to a third invention, in the second invention, further includes a bypass circuit. The bypass circuit is connected in parallel with the boosting means. The control means sets the threshold value to a value obtained by adding the voltage drop of the bypass circuit to the second voltage.

  In a fourth aspect based on the first aspect, the control unit gradually decreases the target voltage from the first voltage to the second voltage from the time when the boosting operation of the boosting unit is started before the engine of the vehicle is started. change.

  In a fifth aspect based on the first aspect, the circuit further comprises a bypass circuit. The bypass circuit is connected in parallel with the boosting means. The control unit changes the target voltage from the first voltage to the second voltage before supplying the power supplied from the battery to the load via the bypass circuit.

  In a sixth aspect based on the fifth aspect, the control means includes voltage difference monitoring means. The voltage difference monitoring means monitors the difference between the voltage of power supplied from the battery and the voltage of power supplied to the load. The bypass circuit includes a switching element. The switching element opens and closes a circuit from the battery to the load in accordance with the control of the control means. The control means closes the switching element when the voltage difference monitored by the voltage difference monitoring means is smaller than a predetermined value.

  In a seventh aspect based on the fifth aspect, the bypass circuit includes a switching element. The switching element opens and closes a circuit from the battery to the load in accordance with the control of the control means. The control means changes the target voltage from the first voltage to the second voltage, then gradually changes the target voltage from the second voltage to the first voltage, and the target voltage returns to the first voltage. Thereafter, the switching element is closed.

  In an eighth aspect based on the seventh aspect, the switching element includes a diode. The diode conducts current in the forward direction from the battery to the load. The control means sets the second voltage lower than a value obtained by subtracting the voltage drop due to the diode from the voltage of the power supplied from the battery.

  In a ninth aspect based on the eighth aspect, the control means sets the first voltage to a value obtained by subtracting a voltage drop in the closed state of the switching element from the voltage of the electric power supplied from the battery.

  In a tenth aspect based on the seventh aspect, the control means obtains a boost signal indicating whether or not boosting by the boosting means is necessary from another device that controls engine start of the vehicle. The control means gradually changes the target voltage from the first voltage to the second voltage from the time when the boost signal changes from a boost failure to a signal indicating that boost is required. Then, the control means gradually changes the target voltage from the second voltage to the first voltage from the time when the boost signal changes from the necessity of boost to a signal indicating that boost is not required.

  In an eleventh aspect based on the first aspect, battery voltage monitoring means is further provided. The battery voltage monitoring means monitors the voltage of power supplied from the battery. The control means obtains a boost signal indicating whether or not boosting by the boosting means is necessary from another device that controls engine start of the vehicle. The control means includes a timer that starts counting from when the boost signal changes from a boost failure to a signal indicating that boost is required. The control means changes the target voltage from the first voltage to the second voltage when the voltage monitored by the battery voltage monitoring means rises to the threshold after the timer counts up.

  According to the first aspect of the invention, after the engine is started, the boosting process using the second voltage lower than the first voltage as the target voltage is performed. Therefore, the output voltage supplied from the battery without boosting process> target It becomes a voltage, and intermittent boosting operation can be prevented. In other words, after the engine is started, voltage fluctuation (ripple) caused by the energy during re-boosting due to the boosting operation can be prevented, and the lights of the vehicle, the lamps provided on the instrument panel, etc. blink, It is possible to suppress the generation of noise in the audio equipment.

  According to the second aspect of the invention, after the battery voltage has dropped due to cranking at the time of engine start, it is possible to detect an increase in battery voltage due to the end of the cranking, and that the engine of the vehicle has started. It can be easily detected.

  According to the third aspect of the invention, the voltage fluctuation can be minimized by changing the target voltage from the first voltage to the second voltage using the threshold value as a criterion.

  According to the fourth aspect of the invention, the target voltage is gradually changed from the first voltage to the second voltage from the time when the boosting operation is started, so that the boosting operation can be performed from the battery without the boosting process when the boosting operation is completed. Since the output voltage to be supplied is larger than the target voltage, intermittent boosting operation can be prevented.

  According to the fifth aspect, intermittent boosting operation can be prevented until power is supplied via the bypass circuit.

  According to the sixth aspect, it is possible to suppress voltage fluctuation when switching from power supply boosted by the boosting means to power supply via the bypass circuit. In addition, when switching to power supply via the bypass circuit, it is possible to prevent power from flowing backward from the load side to the battery side.

  According to the seventh aspect, it is possible to suppress voltage fluctuation when switching from the power supply boosted by the boosting means to the power supply via the bypass circuit. In addition, when switching to power supply via the bypass circuit, it is possible to prevent power from flowing backward from the load side to the battery side.

  According to the eighth and ninth aspects, voltage fluctuations when switching from power supply via the diode to power supply via the switching element can be suppressed.

  According to the tenth aspect of the present invention, the voltage fluctuation caused by the energy at the time of re-boosting by the boosting operation and the voltage fluctuation at the time of switching from the power supply boosted by the boosting means to the power supply via the bypass circuit after the engine start. Can be suppressed.

  According to the eleventh aspect, by using the count value of the timer, it is possible to easily detect after the vehicle engine is started.

(First embodiment)
Hereinafter, with reference to FIGS. 1-4, the electric power supply system containing the power supply control device which concerns on the 1st Embodiment of this invention is demonstrated. Typically, the power supply control device according to the first embodiment is mounted on a vehicle with a so-called idling stop mechanism that automatically stops the engine of the vehicle when the vehicle stops. For example, the idling stop mechanism automatically stops the engine when the vehicle stops due to a signal, etc., when the driver puts the gear in neutral and lifts the foot from the clutch pedal. To restart. FIG. 1 is a schematic block diagram showing an example of the configuration of a power supply system including a power supply control device according to the first embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of the configuration of the booster circuit 3 included in the power supply control device of FIG. FIG. 3 is a flowchart showing an example of an operation in which the power supply control device of FIG. 1 controls the boosting operation. FIG. 4 is a diagram for explaining an example of the relationship between the boosting operation of the power supply control device of FIG. 1 and the output voltage, battery voltage, and target voltage.

  In FIG. 1, the power supply system including the power supply control device includes a control unit 1 a, a booster circuit 3, a unidirectional element (diode) 4, a battery 8, and a load 9. In the power supply system, the power stored in the battery 8 is supplied to the load 9. The control unit 1a, the booster circuit 3, and the unidirectional element (diode) 4 correspond to an example of the power supply control device of the present invention.

  The battery 8 is a power storage device that stores electric power generated by a generator (for example, an alternator) provided in the vehicle and supplies the stored electric power to a load 9. For example, a lead storage battery having a rated voltage of about 12 V is used as the battery 8, but another secondary battery (for example, a nickel metal hydride battery or a lithium ion battery) may be used. The positive terminal of the battery 8 is connected to the load 9 via the booster circuit 3 or the diode 4.

  The load 9 is connected to the power supply line of the battery 8 via the booster circuit 3 or the diode 4. The diode 4 is provided on the power supply line in parallel with the booster circuit 3. The diode 4 has an anode connected to the positive terminal of the battery 8 and a cathode connected to the load 9. That is, when the potential on the battery 8 side is high in the power supply line, the power stored in the battery 8 is supplied to the load 9 via the diode 4.

  The booster circuit 3 constitutes a transformer circuit that boosts the battery voltage Vb of the battery 8 supplied via the power supply line to the output voltage Vo in accordance with an instruction from the controller 1a and outputs the boosted voltage to the load 9. The power supply line is provided in parallel with the diode 4. Therefore, when the potential on the battery 8 side is low in the power supply line and the booster circuit 3 starts the boosting operation, the power stored in the battery 8 is boosted from the battery voltage Vb to the output voltage Vo by the booster circuit 3. Power is supplied to the load 9. For example, the booster circuit 3 is a so-called boost DC-DC converter, and a series or switching converter is used. A detailed configuration example of the booster circuit 3 will be described later.

  The controller 1a controls the operation of the booster circuit 3 to control the output voltage Vo in the power supply system. For example, the control unit 1a includes an ECU (Electronic Control Unit) that monitors the entire power supply system. The control unit 1a includes a voltage drop monitoring unit 11, a voltage rise monitoring unit 12, a target voltage setting unit 13, an output voltage monitoring unit 14, and a booster circuit control unit 15.

  The voltage drop monitoring unit 11 is connected to the power supply line and monitors whether or not the battery voltage Vb of the battery 8 has dropped to a predetermined voltage (decrease determination voltage VbL) or less. The voltage rise monitoring unit 12 is connected to the power supply line and monitors whether or not the battery voltage Vb of the battery 8 has risen again to a predetermined voltage (voltage Vl + Vf) or more after the battery voltage Vb has dropped to the voltage VbL or less. . The target voltage setting unit 13 sets a target voltage to be boosted by the booster circuit 3 in accordance with the monitoring state of the battery voltage Vb in the voltage drop monitoring unit 11 and the voltage rise monitoring unit 12. The output voltage monitoring unit 14 is connected to the power supply line and monitors the output voltage Vo output from the booster circuit 3. When the boosting circuit control unit 15 obtains a signal indicating that boosting is required from a boosting signal indicating whether boosting processing is necessary or not from another device (for example, a control device for an idling stop mechanism that controls start and stop of the engine), In response to the instruction, the booster circuit 3 is controlled to start the boosting process. The booster circuit control unit 15 controls the boosting operation of the booster circuit 3 so that the output voltage Vo becomes the target voltage set by the target voltage setting unit 13 according to the battery voltage Vb and the output voltage Vo.

  Next, an example of the configuration of the booster circuit 3 will be described with reference to FIG. In FIG. 2, the booster circuit 3 boosts the battery voltage Vb of the battery 8 to the output voltage Vo.

  As shown in FIG. 2, the booster circuit 3 includes a coil 32 and a diode 33 on an input / output line connecting the battery 8 and the load 9. The diode 33 is inserted between the coil 32 and the output terminal with the anode on the power supply line side (coil 32 side) of the battery 8 and the cathode on the load 9 side.

  The input / output line between the coil 32 and the anode side of the diode 33 is grounded via the switching element 31. The switching element 31 is composed of, for example, a MOSFET (MOS Field Effect Transistor). When the switching element 31 is composed of a MOSFET, it is inserted with the source grounded and the drain on the input / output line side. The input / output line between the cathode side of the diode 33 and the output terminal (load 9 side) is grounded via the capacitor 34.

  The output voltage applied to the gate of the switching element 31 is controlled by a driver (not shown). The driver is controlled by the control unit 1a (see FIG. 1) and intermittently switches the switching element 31 according to the drive signal Du output from the control unit 1a. The controller 1a operates the booster circuit 3 so that the output voltage Vo becomes the target voltage by intermittently switching the switching element 31 at a frequency corresponding to the target voltage. Since specific intermittent operation is known, detailed description is omitted.

  Next, with reference to FIG. 3 and FIG. 4, operation | movement of the power supply control apparatus controlled by the control part 1a is demonstrated.

  In FIG. 3, the control unit 1a performs initial setting in processing to be described later (step S51), and advances the processing to the next step. For example, the control unit 1a initially sets the target voltage to the reference target voltage Vh, the voltage drop flag Fd to OFF (OFF), and the voltage rise flag Fu to OFF (OFF), and writes the data indicating each to the storage area. To initialize the data. For example, the reference target voltage Vh is set to the output voltage Vo at the present time (before engine start). In this case, the reference target voltage Vh = the current battery voltage Vb−the voltage drop Vf due to the diode 4.

  Next, the control unit 1a determines whether or not the boost signal obtained from another device is a signal indicating the necessity of boost (step S52). For example, as shown in FIG. 4, the control device for the idling stop mechanism that controls the start and stop of the engine needs to boost the battery voltage Vb in preparation for a voltage drop when starting the engine of the vehicle. Is output to the controller 1a (at the time indicated by the arrow A in the drawing). Then, when the boost signal is a signal indicating the need for boost, the control unit 1a proceeds to the next step S53. On the other hand, when the boost signal is a signal indicating that the boost signal is not boosted, that is, the boost process is not performed (for example, the boost signal is low (OFF) at the low (Lo) level), the control unit 1a performs processing in the next step S60. To proceed.

  In step S53, the control unit 1a performs a boosting process according to the target voltage set at the present time, and proceeds to the next step. In the step-up process in step S53, when the output voltage Vo is lower than the target voltage set at the present time, the control unit 1a outputs a drive signal Du at which the output voltage Vo becomes the target voltage to the booster circuit 3. The boosting circuit 3 is caused to perform a boosting operation. On the other hand, when the output voltage Vo is higher than the target voltage set at the present time, a drive signal Du for stopping the boosting operation is output to the booster circuit 3 to stop the boosting operation of the booster circuit 3.

  Next, the control unit 1a determines whether or not the current voltage drop flag Fd is set to ON (step S54). And the control part 1a advances a process to following step S55, when the voltage fall flag Fd is set to OFF (OFF). On the other hand, when the voltage drop flag Fd is set to ON (ON), the controller 1a advances the process to the next step S57.

  In step S55, the control unit 1a determines whether or not the battery voltage Vb has decreased to a predetermined voltage (decrease determination voltage VbL) or less. And the control part 1a advances a process to following step S56, when the battery voltage Vb falls to the fall determination voltage VbL or less. On the other hand, when the battery voltage Vb is higher than the decrease determination voltage VbL, the control unit 1a advances the process to the next step S59. Here, the decrease determination voltage VbL is a determination voltage for detecting a voltage drop of the battery voltage Vb generated when the engine of the vehicle is started. For example, the decrease determination voltage VbL is set to a voltage lower than the rated voltage of the battery 8 by a predetermined voltage. That's fine. For example, as shown in FIG. 4, it is possible to know that the cranking of the engine has started by detecting that the battery voltage Vb has decreased to the decrease determination voltage VbL (at the time indicated by the arrow B in the figure).

  In step S56, the control unit 1a sets the voltage drop flag Fd to ON, updates the data indicating the voltage drop flag Fd, and proceeds to the next step. Thus, the voltage drop flag Fd is set to ON when the battery voltage Vb drops below the drop determination voltage VbL.

  Next, the controller 1a determines whether or not the battery voltage Vb has risen to a predetermined voltage (a value obtained by adding the voltage Vf corresponding to the voltage drop of the diode 4 to the low target voltage Vl) or more ( Step S57). And control part 1a advances processing to the following step S58, when battery voltage Vb rises to voltage Vl + Vf or more. On the other hand, when the battery voltage Vb is lower than the voltage Vl + Vf, the control unit 1a advances the process to the next step S59.

  Here, as will be apparent from the description below, the low target voltage Vl is a voltage that the booster circuit 3 sets as a boost target in the boosting operation after the engine starts, and corresponds to the voltage drop of the diode 4 from the battery voltage Vb before the engine start. It is set to a voltage lower by a predetermined voltage than the value obtained by subtracting Vf. For example, the low target voltage Vl is the battery voltage Vb when the boost signal changes from the low (Lo) level to the high (Hi) level in the determination of the step S52, that is, when the instruction changes from the boost failure to the need for boost. Is set to a voltage that is lower by a predetermined voltage (for example, 100 mV to 200 mV lower) than the value obtained by subtracting Vf corresponding to the voltage drop of the diode 4 from, and consequently set to a voltage that is 100 mV to 200 mV lower than the reference target voltage Vh. Is done.

  Note that other values may be used as the threshold value used in step S57. For example, even if it is determined whether or not the battery voltage Vb has increased to a value obtained by adding Vf corresponding to the voltage drop of the diode 4 to the reference target voltage Vh (that is, the voltage level of the battery voltage Vb before starting the engine). It doesn't matter.

  In step S58, the control unit 1a sets the target voltage to the low target voltage Vl, sets the voltage increase flag Fu to ON, updates the data indicating the target voltage and the voltage increase flag Fu, and then Proceed to the next step.

  Here, step S57 and step S58 are processes performed only when the voltage drop flag Fd is set to ON. In other words, the state in which the battery voltage Vb increases to the voltage Vl + Vf or higher in the determination of step S57 is the voltage before the cranking after the battery voltage Vb has dropped due to the cranking at the time of engine start. It is in a state of rising again to the vicinity and returning. That is, it is possible to determine whether or not the cranking at the time of starting the engine has been completed by the process of step S57. The step S58 is processing when the cranking is completed, that is, when the engine is started, and the target voltage of the booster circuit 3 is changed to the low target voltage Vl after the engine is started. Therefore, in the step-up process in step S53 after the engine is started, the step-up operation is performed at a target voltage (low target voltage Vl) lower than the target voltage (reference target voltage Vh) before starting the engine (shown in FIG. 4). (Point of arrow C in the figure).

  Next, the control unit 1a determines whether or not the boost signal obtained from another device is a signal indicating that boost is not performed (step S59). For example, as shown in FIG. 4, the control device for the idling stop mechanism that controls the start and stop of the engine, when the engine of the vehicle is started, is a signal that changes the instruction from the need for boost to the boost or not, that is, the battery voltage Vb. Is output to the control unit 1a (at the time indicated by the arrow D in the drawing). The boost signal (for example, the boost signal is set to low (Lo) level and turned off) is stopped. Then, when the boost signal is a signal indicating that the boost process is continuously performed (for example, the boost signal is on (ON) at a high (Hi) level), the control unit 1a proceeds to the next step S60. On the other hand, when the boosting signal is a signal indicating that the boosting process is finished (for example, the boosting signal is low (OFF) and off (OFF)), the control unit 1a finishes the boosting process (step S61). Returning to step S51, the process is repeated. Therefore, when instructed to end the boosting process, the control unit 1a ends the boosting process and performs the initial setting in step S51 to initialize each setting.

  In step S60, the control unit 1a determines whether or not to end the process. Conditions for terminating the process include, for example, that the user of the vehicle turns off the ignition key, or that the power supply to the load 9 is stopped by the control of the vehicle. When the process is not ended, the control unit 1a returns to step S52 and repeats the process. When the process is ended, the control unit 1a ends the process according to the flowchart.

  As described above, the power supply control shown in FIG. 3 suppresses the voltage fluctuation after the engine is started. For example, as shown in FIG. 4, after the necessity of boosting is indicated by the boosting signal (after the point of arrow A in the figure), the booster circuit 3 causes the reference target voltage Vh by the voltage drop of the battery voltage Vb due to engine cranking. The boosting operation is performed with the boosting target as the boosting target (period of the boosting operation “present” in FIG. 4). When the battery voltage Vb drops to the drop determination voltage VbL due to the voltage drop (at the time of the arrow B in the figure), the voltage drop flag Fd is set to ON (ON) (period of voltage drop monitoring “ON” in FIG. 4). .

  When the engine cranking is completed and the battery voltage Vb rises to the voltage Vl + Vf, the voltage rise flag Fu is set to ON (ON period), and the booster circuit 3 The step-up operation is switched to the step-up operation with the low target voltage Vl lower than the reference target voltage Vh as the step-up target (at the time indicated by arrow C in the figure). Therefore, after the engine is started, the boosting process is performed with the low target voltage Vl lower than the reference target voltage Vh. Therefore, the output voltage Vo output via the diode 4 is always greater than the low target voltage Vl, and intermittent boosting operation is prevented. can do. That is, after the engine is started, it is possible to prevent the occurrence of voltage fluctuations (ripple) caused by the energy at the time of re-boosting in the booster circuit 3, and the lights on the vehicle and the lamps provided on the instrument panel flicker, It is possible to suppress the occurrence of noise in the audio equipment of the vehicle.

  In the above-described embodiment, the start and end of cranking are detected by the battery voltage Vb rising to the voltage Vl + Vf after the battery voltage Vb has dropped to the drop determination voltage VbL or lower. It does not matter if the ranking starts and ends.

  As an example, as shown in FIG. 5, when the time from the boosting process start instruction by the boosting signal until the engine is started is determined, the start of cranking may be detected using the count value by the timer 16. For example, the control unit 1b includes a timer 16 instead of the voltage drop monitoring unit 11 provided in the control unit 1a. The timer 16 starts counting when an instruction to start boosting processing is given, that is, when the boosting signal changes from a low (Lo) level to a high (Hi) level. Then, when the count value of the timer 16 counts up, it is determined that cranking has started, and the voltage drop flag Fd is changed from OFF (OFF) to ON (ON). Thereafter, the power supply shown in FIG. Processing similar to control is performed.

  Here, the time from the start of counting by the timer 16 to the counting up is not less than the longest time assumed from the time when the boosting process start instruction is given until the battery voltage Vb shows the minimum value, and the boosting is performed. What is necessary is just to set to less than the shortest time assumed in the time from the engine start time to the battery voltage Vb rising to the voltage Vl + Vf from the processing start instruction point.

  Further, in the above-described embodiment, the power supply system in which the diode 4 is provided in parallel with the booster circuit 3 and the normal power supply line and the boosted power supply line are separately provided is used. However, even if the normal power supply line and the boosted power supply line are the same power supply system (for example, a system without a parallel circuit in which the diode 4 is inserted in FIG. 2), the present invention has the same effect. Needless to say.

  In the above-described embodiment, an example in which the target voltage is immediately changed from the reference target voltage Vh to the low target voltage Vl based on a predetermined condition (at the time point indicated by arrow C in FIG. 4) is used. The voltage may be changed from the reference target voltage Vh to the low target voltage Vl. For example, the target voltage is set to the reference target between the time when the battery voltage Vb is detected and the time when it is detected that the battery voltage Vb is increased (from the time point B to the point C in FIG. 4). It may be changed gradually from the voltage Vh to the low target voltage Vl.

(Second Embodiment)
Hereinafter, with reference to FIGS. 6-8, the electric power supply system containing the power supply control apparatus which concerns on the 2nd Embodiment of this invention is demonstrated. Typically, the power supply control device according to the second embodiment of the present invention is also mounted on a vehicle with a so-called idling stop mechanism that automatically stops the engine of the vehicle when the vehicle stops. FIG. 6 is a schematic block diagram showing an example of the configuration of a power supply system including a power supply control device according to the second embodiment of the present invention. FIG. 7 is a flowchart showing an example of an operation in which the power supply control device of FIG. 6 controls the boosting operation. FIG. 8 is a diagram for explaining an example of the relationship between the boost operation of the power supply control device of FIG. 6 and the output voltage, battery voltage, and target voltage.

  In FIG. 6, the power supply system including the power supply control device includes a control unit 1 c, a booster circuit 3, a switching element 5, a diode 6, a battery 8, and a load 9. In the power supply system, the power stored in the battery 8 is supplied to the load 9. The control unit 1c, the booster circuit 3, the switching element 5, and the diode 6 correspond to an example of the power supply control device of the present invention.

  Compared with the power supply system including the power supply control device according to the first embodiment shown in FIG. 1, the power supply system including the power supply control device according to the second embodiment includes the switching element 5 and the diode 4 instead of the diode 4. A set of diodes 6 is used, and the configuration of the control unit 1c is different. Since the other configuration of the power supply system including the power supply control device according to the second embodiment is the same as that of the power supply system including the power supply control device according to the first embodiment, the same components are the same. The detailed description is abbreviate | omitted.

  For example, when the switching element 5 is constituted by a MOSFET, the diode 6 is constituted by a parasitic diode of the MOSFET. When the switching element 5 is formed of a MOSFET, the source is connected to the positive terminal of the battery 8 and the drain is connected to the load 9, the anode of the diode 6 is on the positive terminal side of the battery 8, and the cathode is on the load 9 side. . Thus, by connecting the switching element 5 in parallel with the booster circuit 3, the voltage drop when supplying the power of the battery 8 to the load 9 is reduced.

  For example, when power is supplied through the diode 4 in the power supply system used in the first embodiment, a voltage drop in the diode 4 is about 1.0V. On the other hand, when power is supplied via the switching element 5 in the power supply system used in the second embodiment, the voltage drop in the switching element 5 is very small, so the condition for supplying power from the battery 8 to the load 9 is advantageous. Become.

  Here, when the switching element 5 is turned on (closed) after the boosting operation by the booster circuit 3 is stopped, the diode 6 is interposed between the stop of the boosting operation and the switching element 5 being turned on (closed). Generally, a period for supplying power is provided. This is because if the boosting operation is stopped and the switching element 5 is immediately turned on (closed), power may flow backward from the load 9 to the battery 8 when the output voltage Vo is higher than the battery voltage Vb. In this case, the backflow is prevented by supplying power through the diode 6 once.

  However, during the period when power is supplied from the battery 8 to the load 9 via the diode 6, a voltage drop (for example, the voltage Vf is reduced) due to the diode 6 occurs. Therefore, when the switching element 5 is turned on (closed) in this state, the output voltage Vo rises by the voltage Vf. The voltage Vf that causes a voltage drop varies depending on the elements constituting the diode 6, but is usually a voltage Vf = 0.4V to 1.0V. Therefore, when the switching element 5 is turned on (closed), a voltage fluctuation occurs in the output voltage Vo. In the power supply control device according to the second embodiment, intermittent boosting operation after engine startup is prevented, and voltage fluctuation when the switching element 5 described above is turned on (closed) is prevented.

  The controller 1a controls the operation of the booster circuit 3 to control the output voltage Vo in the power supply system. For example, the control part 1c is comprised by ECU which monitors the whole electric power supply system similarly to the control part 1a. The control unit 1 c includes a battery voltage monitoring unit 17, an output voltage monitoring unit 18, a voltage comparison unit 19, a target voltage setting unit 20, and a booster circuit control unit 21.

  The battery voltage monitoring unit 17 is connected to a power supply line from the battery 8 to the load 9 and monitors the battery voltage Vb of the battery 8. The output voltage monitoring unit 18 is connected to the power supply line and monitors the output voltage Vo to the load 9. The voltage comparison unit 19 compares the battery voltage Vb monitored by the battery voltage monitoring unit 17 with the output voltage Vo monitored by the output voltage monitoring unit 18, and the difference is less than a certain value after the engine is started (for example, It is determined whether or not the difference is a difference in voltage drop due to an ON resistance of the switching element 5 (for example, a difference in voltage Von). The target voltage setting unit 20 sets a target voltage to be boosted by the booster circuit 3 in accordance with a boost signal obtained from another device (for example, a control device for an idling stop mechanism that controls starting and stopping of the engine). . When the boosting circuit control unit 21 acquires a boosting signal indicating that boosting is required, the boosting circuit control unit 21 starts the boosting process by controlling the boosting operation of the boosting circuit 3 and the opening / closing operation of the switching element 5 according to the instruction indicating the need for boosting. Then, the booster circuit control unit 21 controls the boosting operation of the booster circuit 3 so that the output voltage Vo becomes the target voltage set by the target voltage setting unit 20, and the switching element 5 is based on the comparison result of the voltage comparison unit 19. Controls the opening and closing operation.

  Here, the output voltages applied to the gates of the switching element 5 and the switching element 31 (see FIG. 2) are controlled by drivers (not shown). The driver is controlled by the control unit 1c, opens and closes the switching element 5 according to the drive signal Dg output from the control unit 1c, and intermittently switches the switching element 31 according to the drive signal Du output from the control unit 1c. .

  Next, with reference to FIG. 7 and FIG. 8, operation | movement of the power supply control apparatus controlled by the control part 1c is demonstrated.

  In FIG. 7, the control unit 1c performs initial setting (step S81), and proceeds to the next step. For example, the control unit 1c initializes the target voltage Vt to the initial value Vi, writes data indicating the target voltage Vt in the storage area, and initializes the data.

  Next, the controller 1c determines whether or not the boost signal obtained from another device is a signal indicating the need for boost (step S82). For example, as shown in FIG. 8, the control device for the idling stop mechanism that controls the start and stop of the engine, when starting the vehicle engine, boosts the battery voltage Vb in preparation for a voltage drop. (For example, the boost signal is set to high (Hi) level and turned on (ON)) is output to the control unit 1c (at the time indicated by an arrow E in the drawing). Then, when the boost signal is a signal indicating the need for boost, the control unit 1c advances the processing to the next step S83. On the other hand, when the boosting signal is a signal indicating that the boosting is not performed, that is, a signal indicating that the boosting process is not performed (for example, the boosting signal is low (Lo) level and off (OFF)), the next step is performed. The process proceeds to S91.

  In step S83, the control unit 1c performs a boosting process according to the target voltage Vt (initial value Vi) set at the present time, and proceeds to the next step. For example, the initial value Vi is set to the current output voltage Vo (before the engine is started). In this case, the initial value Vi = current battery voltage Vb−voltage drop (voltage Von) due to the ON resistance of the switching element 5. It becomes.

  It is assumed that the boosting process started in step S83 is continuously performed until the boosting process ends in step S90 described later, and the control unit 1c outputs the output voltage Vo from the target voltage Vt set at each time point. Is low, the drive signal Du at which the output voltage Vo becomes the target voltage Vt is output to the booster circuit 3 to cause the booster circuit 3 to perform a boost operation. On the other hand, when the output voltage Vo is higher than the target voltage Vt set at each time point, the drive signal Du for stopping the boosting operation is output to the boosting circuit 3 to stop the boosting operation of the boosting circuit 3.

  Next, the controller 1c turns off (opens) the switching element 5 and turns off the gate drive (OFF) (step S84), and proceeds to the next step. For example, the control unit 1 c outputs the drive signal Dg that turns off (opens) the switching element 5 to the driver of the switching element 5, thereby turning off (opening) the switching element 5.

  Next, the control unit 1c sets the currently set target voltage Vt lower by a predetermined value (subtraction value ΔVd) (Vt−ΔVd) and uses data indicating the newly set target voltage Vt. The data written in the storage area is updated (step S85), and the process proceeds to the next step. The subtraction value ΔVd subtracted from the target voltage Vt is set to a value that gradually decreases the target voltage Vt so that the target voltage becomes Vb−Vf−α when the engine of the vehicle starts (at the end of cranking). (Pointed to by arrow G in FIG. 8). Here, Vf is a voltage assuming a voltage drop due to the diode 6, and is set to 0.4 V to 1.0 V, for example. Α is a value for setting the target voltage Vt to a value lower than the output voltage Vo by a predetermined voltage when the output voltage Vo becomes the voltage Vb−Vf, and is set to, for example, 50 mV to 200 mV.

  Next, the control unit 1c determines whether or not the boost signal obtained from another device is a signal indicating that boost is not performed (step S86). For example, as shown in FIG. 8, the control device for the idling stop mechanism that controls the start and stop of the engine stops the boost of the battery voltage Vb, that is, a signal indicating that the boost is not performed when the engine of the vehicle is started. An instructed boost signal (for example, the boost signal is set to low (Lo) level and turned off) is output to the controller 1c (at the time indicated by an arrow G in the drawing). Then, when the boost signal is a signal indicating that the boost process is continuously performed (for example, the boost signal is on (ON) at the high (Hi) level), the control unit 1c repeats the process of step S85. On the other hand, when the boosting signal is a signal indicating that the boosting process ends (for example, the boosting signal is low (OFF) and off (OFF)), the control unit 1c proceeds to the next step S87.

  In step S87, the currently set target voltage Vt is set higher by a predetermined value (added value ΔVu) (Vt + ΔVu) and written to the storage area using data indicating the newly set target voltage Vt. Update the data and proceed to the next step. The added value ΔVu added to the target voltage Vt is an increase value per unit time for gradually increasing the target voltage Vt from the voltage Vb−Vf−α to the voltage Vb−Von, and the target voltage Vt is increased to the voltage Vb−Von. It is set in accordance with the time to increase to (the time from arrow G to arrow I shown in FIG. 8). Here, Von is a voltage assuming a voltage drop due to the ON resistance of the switching element 5.

  Next, the controller 1c determines whether or not the difference between the battery voltage Vb and the output voltage Vo is equal to or less than a certain value (step S88). Specifically, when the output voltage Vo is lower than the battery voltage Vb by a voltage drop (voltage Von) due to the ON resistance of the switching element 5, the difference between the battery voltage Vb and the output voltage Vo is Judged to be below a certain value. And the control part 1c advances a process to following step S89, when the difference of the battery voltage Vb and the output voltage Vo is below a fixed value. On the other hand, when the battery voltage Vb is higher than the output voltage Vo with a difference larger than the certain value, the control unit 1c repeats the process of step S87.

  In step S89, the control unit 1c turns on the switching element 5 to turn on the gate drive (ON), and proceeds to the next step. For example, the control unit 1 c outputs the drive signal Dg that turns on (closes) the switching element 5 to the driver of the switching element 5 to turn on (close) the switching element 5. As a result, power from the battery 8 is supplied to the load 9 via the switching element 5.

  Next, the control part 1c complete | finishes the pressure | voltage rise process performed continuously from said step S83 (step S90), and advances a process to the next step.

  Next, the control unit 1c determines whether or not to end the process. Conditions for terminating the process include, for example, that the user of the vehicle turns off the ignition key, or that the power supply to the load 9 is stopped by the control of the vehicle. The control unit 1c returns to step S81 when the process is not terminated, repeats the process, and terminates the process according to the flowchart when the process is terminated.

  In this way, the power supply control shown in FIG. 7 suppresses the voltage fluctuation after the engine is started and the voltage fluctuation when the switching element 5 is turned on (closed). For example, as shown in FIG. 8, after the boost signal has changed from an instruction indicating that boosting is not required to an instruction indicating that boosting is required, that is, after the start of boosting processing has been instructed (after the time point indicated by arrow E in the figure), The switching element 5 is turned off (opened) by the voltage drop of the battery voltage Vb due to the ranking, and the booster circuit 3 performs a boosting operation by gradually decreasing the target voltage Vt (from the time point indicated by arrows E to G). period).

  On the other hand, after the battery voltage Vb largely drops due to the cranking operation of the engine, the battery voltage Vb rises to the voltage before starting the engine when the cranking operation ends. As the battery voltage Vb rises, the voltage of the electric power supplied via the diode 6 rises to Vb−Vf, so that the target voltage Vt, which is gradually decreasing, eventually becomes a voltage Vb−Vf or less (a state occurs). (Indicated by arrow F). Accordingly, since the voltage supplied via the diode 6 is higher than the voltage boosted by the booster circuit 3, the state where the output voltage Vo is constant at the voltage Vb−Vf continues.

  When the boost signal changes from an instruction indicating that boosting is required to an instruction indicating that boosting is not required, that is, when the end of the boosting process is instructed, the target voltage Vt is reduced to the voltage Vb−Vf−α, and the output voltage Vo Continues to be constant at the voltage Vb-Vf (at the time of the arrow G in the figure). When the end of the boosting process is instructed by the boosting signal, the boosting circuit 3 performs the boosting operation by gradually increasing the target voltage Vt to the voltage Vb-Von (from the time point indicated by the arrow G to the time point indicated by the arrow I). period). Due to the increase of the target voltage Vt, a state in which the target voltage Vt, which is gradually increased, becomes equal to or higher than the voltage Vb−Vf supplied via the diode 6 (at the time indicated by an arrow H in the drawing). Therefore, since the voltage supplied via the diode 6 is lower than the voltage boosted by the booster circuit 3, the output voltage Vo gradually increases as the target voltage Vt increases (from the time indicated by the arrow H to the arrow in the figure). Period of time I).

  Then, when the target voltage Vt rises to the voltage Vb−Von and the output voltage Vo rises to the voltage Vb−Von, it is determined that the difference between the battery voltage Vb and the output voltage Vo is equal to or less than a certain value (illustrated). (Point of arrow I). When it is determined that the difference between the battery voltage Vb and the output voltage Vo is equal to or less than a certain value, the switching element 5 is turned on (closed), so that the electric power stored in the battery 8 passes through the switching element 5 via the load 9. (After the time point of arrow I).

  Therefore, in the period from the time indicated by the arrow F to the time indicated by the arrow H after the engine is started, the battery voltage Vb−Vf> the target voltage Vt is always satisfied, and the power supply period via the diode 6 is always established. Further, during the period from the time indicated by the arrow H to the time indicated by the arrow I after the engine is started, the battery voltage Vb−Vf <the target voltage Vt is always satisfied, and the boost operation is always performed. That is, intermittent boosting operation can be prevented during the period from the arrow F point to the arrow I point after the engine is started, and voltage fluctuation (ripple) caused by energy at the time of re-boosting in the booster circuit 3 is generated. Can be prevented.

  Further, at the time when the switching element 5 is turned on (closed) after the engine is started (at the time of arrow I), the output voltage Vo rises to the voltage Vb−Von by the boosting operation of the booster circuit 3. Therefore, when the switching element 5 is turned on (closed), the voltage difference between the input side and the output side of the switching element 5 becomes the voltage difference Von, which is a difference in voltage drop due to the on (ON) resistance of the switching element 5. That is, even if the switching element 5 is turned on (closed) in this state, the output voltage Vo does not fluctuate. As described above, when the difference between the battery voltage Vb and the output voltage Vo is less than a certain value, the switching element 5 is turned on (closed) and the boosting operation is stopped to turn on the switching element 5. It is possible to prevent voltage fluctuations when closing. In this way, by preventing each voltage fluctuation that occurs after the engine is started, it is possible to prevent the lights on the vehicle and the lamps provided on the instrument panel from flickering or noise from being generated in the audio equipment of the vehicle. can do.

  In the above-described embodiment, when the target voltage Vt is gradually decreased and when the target voltage Vt is gradually increased, the target voltage Vt is linearly changed. However, the target voltage Vt is changed in another manner. It doesn't matter. For example, the target voltage Vt may be changed nonlinearly in at least one of the process of lowering the target voltage Vt and raising the target voltage Vt. As an example, the target voltage Vt can be easily changed non-linearly by using a capacitor and a resistor (CR circuit).

  Further, when the target voltage Vt is decreased gradually, a lower limit value (for example, lower limit value = Vb−Vf−α) of the target voltage Vt may be provided. In this case, even if the boost signal indicating the end of the boosting process is not yet acquired when the target voltage Vt is lowered to the lower limit value, the process of lowering the target voltage Vt is finished and the target voltage Vt is kept at the above lower limit value. Set to. As a result, even when the cranking operation at the time of starting the engine is long, the target voltage Vt does not extremely decrease, and the time for increasing the target voltage Vt thereafter becomes constant. That is, it is possible to prevent the time for the entire boost control process described above from being prolonged.

  In the above-described embodiment, an example in which the target voltage Vt is gradually decreased from the initial value Vi to the voltage Vb−Vf−α based on a predetermined condition is used. Alternatively, the target voltage Vt may be changed immediately. For example, when the battery voltage Vb drops below a predetermined voltage, the target voltage Vt is immediately changed from the initial value Vi to the voltage Vb-Vf-α, and a boost signal indicating that the boost process is terminated is acquired. Until the target voltage Vt is set to the voltage Vb−Vf−α. As described above, even if the target voltage Vt is set to be low immediately, the intermittent boosting operation after the engine start can be similarly prevented.

  Further, it is needless to say that the above-described voltage setting values and the like are merely examples, and the present invention can be realized even with other voltages. In addition, it goes without saying that the power supply system of the present invention can be applied to the above-described power supply system even if the power supply system has a rated voltage of 12V, 24V, or 42V. Needless to say, the power supply control device of the present invention can also be applied to a vehicle equipped with a hybrid system in which a high-voltage nickel-metal hydride battery or the like is used as a power storage device.

  Although the present invention has been described in detail above, the above description is merely illustrative of the present invention in all respects and is not intended to limit the scope thereof. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention.

  The power supply control device according to the present invention can suppress voltage fluctuation after the engine is started, and can be applied to a power supply system mounted on a vehicle with an idling stop mechanism.

1 is a schematic block diagram showing an example of a configuration of a power supply system including a power supply control device according to a first embodiment of the present invention. Schematic showing an example of the configuration of the booster circuit 3 included in the power supply control device of FIG. The flowchart which shows an example of the operation | movement which the power supply control apparatus of FIG. 1 controls pressure | voltage rise operation. The figure for demonstrating an example of the relationship between the pressure | voltage rise operation of the power supply control device of FIG. 1, an output voltage, a battery voltage, and a target voltage. The schematic block diagram which shows an example of a structure of the electric power supply system containing the other example of the power supply control apparatus of FIG. The schematic block diagram which shows an example of a structure of the electric power supply system containing the power supply control apparatus which concerns on the 2nd Embodiment of this invention. The flowchart which shows an example of the operation | movement in which the power supply control device of FIG. 6 controls the boosting operation. The figure for demonstrating an example of the relationship between the pressure | voltage rise operation of the power supply control device of FIG. 6, an output voltage, a battery voltage, and a target voltage. Schematic block diagram showing an example of the configuration of a conventional power supply system The figure for demonstrating an example of the voltage boost operation | movement of the conventional power supply system, and the relationship between an output voltage and a battery voltage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Control part 11 ... Voltage drop monitoring part 12 ... Voltage rise monitoring part 13, 20 ... Target voltage setting part 14 ... Output voltage monitoring part 15, 21 ... Booster circuit control part 16 ... Timer 17 ... Battery voltage monitoring part 18 ... Output Voltage monitoring unit 19 ... Voltage comparison unit 3 ... Boost circuit 5, 31 ... Switching element 32 ... Coil 34 ... Capacitor 4, 6, 33 ... Diode 8 ... Battery 9 ... Load

Claims (11)

A power supply control device for supplying electric power stored in a battery to a vehicle load,
Boosting means for boosting the voltage of power supplied from the battery and supplying the voltage to the load;
Control means for controlling the voltage boosted by the boosting means,
The control means controls the target voltage boosted by the boosting means before starting the engine of the vehicle to a first voltage, and the second voltage lower than the first voltage after starting the engine of the vehicle. Change the power control device. Battery voltage monitoring means for monitoring the voltage of the electric power supplied from the battery;
2. The control unit according to claim 1, wherein the control unit changes the target voltage from the first voltage to the second voltage when the voltage monitored by the battery voltage monitoring unit rises to a threshold value after dropping. Power supply control device. A bypass circuit connected in parallel with the booster;
The power supply control device according to claim 2, wherein the control unit sets the threshold value to a value obtained by adding a voltage drop of the bypass circuit to the second voltage.   2. The control unit according to claim 1, wherein the control unit gradually changes the target voltage from the first voltage to the second voltage from the time when the boosting operation of the boosting unit is started before the engine of the vehicle is started. The power supply control device described. A bypass circuit connected in parallel with the booster;
The control unit changes the target voltage from the first voltage to the second voltage before supplying the power supplied from the battery to the load via the bypass circuit. The power supply control device described. The control means includes voltage difference monitoring means for monitoring a difference between a voltage of power supplied from the battery and a voltage of power supplied to the load,
The bypass circuit includes a switching element that opens and closes a circuit from the battery to the load in accordance with control of the control means,
The power supply control device according to claim 5, wherein the control unit closes the switching element when the voltage difference monitored by the voltage difference monitoring unit is smaller than a predetermined value. The bypass circuit includes a switching element that opens and closes a circuit from the battery to the load in accordance with control of the control means,
The control means changes the target voltage from the first voltage to the second voltage, and then gradually changes the target voltage from the second voltage to the first voltage. The power supply control device according to claim 5, wherein the switching element is closed after the voltage returns to the first voltage. The switching element includes a diode that allows a current to flow in a forward direction from the battery to the load;
The power supply control device according to claim 7, wherein the control unit sets the second voltage lower than a value obtained by subtracting a voltage drop due to the diode from a voltage of electric power supplied from the battery.   The power supply control device according to claim 8, wherein the control unit sets the first voltage to a value obtained by subtracting a voltage drop when the switching element is closed from a voltage of power supplied from the battery. The control means obtains a boost signal indicating whether or not boosting by the boosting means is necessary from another device that controls engine start of the vehicle,
The control means gradually changes the target voltage from the first voltage to the second voltage from the time when the boost signal is changed from a boost failure to a signal indicating the need for boost,
8. The control unit according to claim 7, wherein the control unit gradually changes the target voltage from the second voltage to the first voltage from a point in time when the boost signal is changed from a boost request to a signal indicating a boost failure. Power control device. Battery voltage monitoring means for monitoring the voltage of the electric power supplied from the battery;
The control means obtains a boost signal indicating whether or not boosting by the boosting means is necessary from another device that controls engine start of the vehicle,
The control means includes a timer that starts counting from a point in time when the boost signal is changed from a boost failure to a signal indicating that boost is required.
The control means changes the target voltage from the first voltage to the second voltage when the voltage monitored by the battery voltage monitoring means rises to a threshold after the timer counts up. The power supply control device according to 1.

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